Best Answer

If she's spayed this shouldn't happen, but if she's in tact it's likely. As a part of their heat cycle a female dog's mammaries will swell. They may go back to what they were, or they may stay a bit bigger than they were before her first heat. A dog may even lactate even if she wasn't bred! All normal possibilities.

Even if you're just waiting to spay her, reproductive health is part of overall health and any changes that seem odd or that you're not sure about should be discussed with your vet.

Meridian answered on Jun 18th.